1. Tunis-2014, April 3 rd

2. The beginning of charging was January 2009 and the beginning of monitoring of the impact of the treated wastewater was June 2, 2009. The estimated volume of treated wastewater was 511000 m 3 yr -1. Objectives Impact of these treated water on: piezometric levels, water salinity, major and trace elements, NH 4, NO 2 and NO 3, role of the sand filter (unsaturated zone) during the infiltration- percolation period in retention of organic and metallic pollutants. Tunis-2014, April 3 rd

3. - Physico-chemical parameters * salinity in summer 3.8 g L -1 -5 g L -1, in winter 2 g L -1 - 2 g L -1, * pH in summer 8-8.4, in winter 7.8-8.2 - The mean concentrations of NH 4 +, NO 2 -, NO 3 - and PO 4 3- are 2.35 mgL -1, 0.35 mg L -1, 2.82 mgL -1, 2.86 mgL -1, respectively. - The mean concentrations of DBO 5 et DCO are 22 mgL - 1, 176 mgL -1, respectively - HAPs : the range concentrations of HAPs are 1,574 10 -5 and 0.0162 mgL -1  Tunis-2014, April 3 rd

5. Piezometric levels evolution Tunis-2014, April 3 rd

8. Piezometric variation 2008-2012 recharge period: (a)Map dry seasons; (b) map rainy seasons; (c section of dry seasons; (d) section of rainy seasons Tunis-2014, April 3 rd

11. Spatial distribution of the salinity in dry seasons of 2009, 2010, 2011 and 2012 Tunis-2014, April 3 rd

13. Major elements a b variation of the mean Calcium Concentrations variation of the mean Magnesium Concentrations Tunis-2014, April 3 rd

14. Nutritious salts Tunis-2014, April 3 rd

17. Retention capacity of the topsoil in refill basins Good retention capacity of sand in non-saturate zone for organic matter, organic and metallic pollutants Tunis-2014, April 3 rd

18. a- The used water quality is acceptable b- During the first four years (December 2008-December 2012), 1.41 Mm3 was infiltrated to the aquifer. - Gradually increasing of piezometric levels: exceeding 1.5 m in some region. - Improvement of groundwater quality: * decrease of the ground water salinity in a 2 km-wide band parallel to the coastline, * decrease of majors and nutrious salts concentrations Tunis-2014, April 3 rd

19. Consequently - Acceptable primary results of artificial recharge by treated wastewater - Hydraulic barrier was formed in the side of the sea which resist against to the seawater intrusion. Recommendation - Because the aquifer situation is still characterized by piezometric depression and high salinity values, we suggest to continue the groundwater artificial recharge by treated wastewater - The monitoring must continued with bacterial analysis - Bacterial analysis ? - Effects of unsaturated zone on water depollution Tunis-2014, April 3 rd